I see the 6025W-NTR+B supports 8 SATA/SAS, but only 6 SATA ports is pre-configured on server. If I add a RAID card like the 8-port Areca ARC-1220, would I be able to use all 8 hard drives?
Yes, you can add the areca 1220 8ports or other manufacture 8ports RAID controller to fill up all 8ports on the backplane with SATA (discrete) cables.